That's what we are doing this weekend to our old traps. Started building Circle or "6" pen traps instead of the normal hog traps to keep the deer from getting trapped.

I’m assuming those that are cutting the tops off aren’t doing this on 4x4x8 traps. If you do the big hogs will climb out. This would only be a good option on a circle pen.

I caught a little buck in my hog trap once. Once! that's all it took. I felt terrible for that little guy. He busted his nose all up trying to get out.

I sprayed my trap door and frame with WD40 as suggested by bigdave, deer ate all the corn scattered around the trap but didn’t touch the corn inside. The pile of corn in the trap sat for three days with deer visiting the area both morning and evening each day.
No hogs yet but I expect that will change once the wheat starts sprouting in the surrounding fields.

Now add (a little bit) of diesel to the corn in the trap. Diesel will act as an attractive to the hogs.
You can put the diesel at the front of the trap just inside the door and then some at the back of the trap.
It does not take much at all; about a measuring cup worth.(1/2 in front and 1/2 in back) Good luck

I built traps for a living and one of my big sellers was a "deer proof" trap. A 4x8 with open top but with a rail around the top, hogs have short legs and can not escape over that rail but deer, turkeys, exotics were able to jump out.

That sounds like it may work. I watched a hog literally climb out of an open top trap and on a different day a pen made of hog panels. Looked like a human sticking its legs in the holes of the panels and climbing right out. Wouldn't have believed it if I didn't see it. Also had a big boar bust out of the top of my trap that had a top but wasn't bolted together very tightly. Couldn't believe it made it out but I'm guessing he did the same thing and climbed out once he busted the top off.

I caught up with him the next weekend though. Guess he thought he could get out again.

Would love more info on how you built that trap Simple!

I have a 7 panel, 4ft tall, electric gated, open top pen. I have hogs go in; I set the gate they eat everything lay down for a while get up walk over and climb out. People say once a hog has been in a trap they wont go back in WRONG I caught the same hog 2 nights in a row and he climbed out both nights. Now my trap is a large 7 panel pen. 4ft tall is not tall enough on an open top pen if a large trap. I seen plenty of hogs climb out of a 4ft panel. I have pipe on top blocking all corners and they go right over in the middle of a straight panel. Now a 150 pound pig I have not had one make it over yet, they get 3/4 of the way up in the corners and the pipe puts them back in. Put the diesel and wd40 and deer wont go in. Problem solved

Nice Trap

Big Dave, your advise on spraying WD 40 around the door worked very well. Deer fed around the trap all week, but none went inside the trap. I caught a nice Sow in the trap on the 4th day it was set. I’ll refresh to WD 40 when I rebait the trap. Thanks for the advise.

We have the standard 4X4X8' trap. Caught deer, put rebar down low and still caught deer. Finally we took all the trip wire etc off, laid the trap on it's side where gravity kept the door closed. We just bait through the upside and put a rock under the door to hold it up a few inches. The pigs just push their way in but we have never caught another deer since then.The heard the pigs push on the door the tighter it closes. When we aren't there we bungee the door open.

Thanks, that is what has worked for me and many others I have shared with. You might try the diesel on the corn. I was hesitant at the start to try diesel, but it works great, a splash at the front and at the back of the trap
works as an attractant.
The smell stays for a good while. I will ware gloves or use a bottle of scent away to spray down where I touch the trap with my hands for cover scent. Good luck and keep catching them hogs.